LOCATION RALPH SD+MTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Aridic Argiustolls
TYPICAL PEDON: Ralph loam - on a north-facing slope of 5 percent under native grass. (Colors are for dry soil unless otherwise stated.)
A--0 to 6 inches; grayish brown (2.5Y 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, friable; many fine roots; neutral; clear smooth boundary. (3 to 7 inches thick)
Bt--6 to 17 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; weak medium prismatic structure parting to moderate medium subangular blocky and blocky; slightly hard, friable; common fine roots; shiny films on faces of peds; neutral; clear wavy boundary. (7 to 17 inches thick)
Btk--17 to 27 inches; light brownish gray (2.5Y 6/2) clay loam, olive brown (2.5Y 4/4) moist; moderate medium and coarse prismatic structure parting to moderate medium and coarse blocky; hard, firm, slightly sticky and slightly plastic; common fine roots; patchy films on faces of peds; many medium accumulations of carbonate; violent effervescence; slightly alkaline; clear wavy boundary. (0 to 12 inches thick)
Bk--27 to 34 inches; light brownish gray (2.5Y 6/2) clay loam, olive brown (2.5Y 4/4) moist; weak medium and coarse subangular blocky structure; slightly hard, friable; few fine roots; many medium accumulations of carbonate; violent effervescence; slightly alkaline; clear wavy boundary. (5 to 20 inches thick)
Cr1--34 to 51 inches; gray (5Y 6/1 and 5/1) soft shale, olive gray (5Y 4/2) and very dark gray (5Y 3/1) moist; many medium prominent mottles of yellowish red (5YR 4/6) moist; bedded; strong effervescence; moderately alkaline; clear wavy boundary.
Cr2--51 to 60 inches; pale olive (5Y 6/3) soft sandstone, olive (5Y 5/3) moist; common fine prominent mottles of strong brown (7.5YR 5/6) moist; slight effervescence; slightly alkaline.
TYPE LOCATION: Butte County, South Dakota; about 1 mile east and 13 miles north of Castle Rock; 1400 feet south and 700 feet west of the northeast corner of sec. 29, T. 14 N., R. 6 E.
RANGE IN CHARACTERISTICS: Depth to carbonate typically is about 13 to 17 inches and ranges from 10 to 24 inches. Depth to siltstone, sandstone, or silty shale typically is about 28 to 36 inches and ranges from 20 to 40 inches. The mollic epipedon ranges from 7 to 11 inches in thickness after mixing and commonly extends into the Bt horizon.
The A horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 2 or 3 moist, and chroma of 2 or 3. It is loam, silt loam, or very fine sandy loam and is neutral or slightly alkaline.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 3 or 4 moist, and chroma of 2 to 4. It is loam, clay loam, or silty clay loam and typically contains between 24 and 28 percent clay, but ranges from 18 to 35 percent and contains less than 15 percent fine sand or coarser. It is neutral or slightly alkaline.
The Btk and Bk horizons have hue of 10YR or 2.5Y, value of 6 to 8 and 4 to 6 moist, and chroma of 2 to 4. They are clay loam, silty clay loam, silt loam or loam. They contain disemminated carbonate and few to many, fine to coarse accumulations of carbonate. They are slightly alkaline or moderately alkaline. The lower Bk horizon contains up to 50 percent by volume of weathered fragments of soft bedrock.
Some pedons have a C horizon.
The Cr horizon is silty shales, siltstones, or fine-grained sandstones containing free carbonate. It is slightly alkaline or moderately alkaline.
COMPETING SERIES: These are the Brussett, Norkool, Vassett, and Waas series. All of these soils do not have a paralithic contact within a depth of 40 inches.
GEOGRAPHIC SETTING: Ralph soils are on nearly level, undulating and rolling uplands. Slope gradients range from 0 to 9 percent. Ralph soils formed in silty material weathered from calcareous silty shales, siltstone or fine grained sandstone. Mean annual temperature ranges from 39 to 45 degrees F, and mean annual precipitation ranges from 14 to 15 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cabbart and Scroggin soils. Cabbart and Scroggin soils do not have a mollic epipedon or argillic horizon. In addition, Cabbart soils have bedrock at depths of 10 to 20 inches. Cabbart soils are on the steeper hilltops and ridges. Scroggin soils are on similar landscapes as Ralph soils.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is low to medium. Permeability is moderate above the bedrock.
USE AND VEGETATION: Used for cropland and rangeland. Cultivated areas are used for growing small grains, hay, and pasture. Native vegetation is mainly western wheatgrass, little bluestem, green needlegrass, needleandthread, prairie sandreed, blue grama, sedges and forbs.
DISTRIBUTION AND EXTENT: Northwestern South Dakota. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Butte County, South Dakota, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of about 7 inches after mixing (A horizon); argillic horizon - the zone from a depth of about 6 to 27 inches (Bt and Btk horizons).